Heat exchangers are utilized in various technical applications for transferring heat from one fluid to another fluid. Heat exchangers are especially used in motor vehicles as charge-air coolers to cool the air, which is compressed by a compressor, ahead of being supplied to the engine. Here, the charge air, which is to be cooled, and a cooling liquid are passed through the heat exchanger. The cooling liquid or coolant takes up heat from the charge air and thereby cools the charge air. Heat exchangers of this kind are subjected to high loads as a consequence of temperature changes because, during operation of the motor vehicle, temperature fluctuations occur and, furthermore, for each start of the engine, the heat exchanger is at first cold.
Heat exchangers in a plate configuration are often used for charge-air coolers. Many plates are stacked one atop the other. Because of the geometry of the plates, channels, that is, fluid channels, for the charge air and the coolant are formed between the plates. End plates are mounted at the respective ends of the stack. The intermediate plates and the end plates are, in general, firmly bonded to each other by soldering. The thickness of the end plates is significantly greater than the thickness of the intermediate plates.
Distortions within the heat exchanger occur because of thermal cycling and/or because of an inhomogeneous temperature distribution within the heat exchanger. The distortions result especially from the larger thermal inertia of the end plates compared to the intermediate plates. The end plates have a greater thickness and therefore a larger mass so that the end plates heat up significantly slower or cool down slower than the intermediate plates. Furthermore, the stiffness of the end plates parallel to a plate plane is greater than the stiffness of the intermediate plates parallel to an intermediate plate plane. This difference in stiffness between the end plates and the intermediate plates can lead to damage that becomes manifest by a limited service life for the heat exchanger. Changes in size of the end plate because of temperature changes parallel to the plate plane differ from the change in size for temperature changes at the intermediate plate next to the end plate parallel to the intermediate plate plane.